King-pin actuated landing gear for road-haulage semi-trailers

ABSTRACT

A road-haulage semi-trailer having a sliding king-pin for lifting the landing legs to the retracted position, the landing legs being spring-biassed towards the retracted position and coupled to the king-pin through a rack and pinion to give rapid lifting of the legs with a small king-pin movement. The king-pin is disengageable to move independently of the landing legs over a large distance between front and rear clamps which enable it to be locked in either a front or a rear position for travelling.

0 United States Patent [191 [111 3,790,190

Davis Feb. 5, 1974 [54] KING-PIN ACTUATED LANDING GEAR 1,766,780 6/1930Finch... 280/428 D ROAD HAULAGE SEMLTRAILERS 2,418,240 4/1947 Starr280/430 3,456,962 7/1969 Swepa 280/430 [76] Inventor: Carlton JohnDavis, 101,

Chesterfield Rd., Leyton, London, England [22] Filed: Apr. 13, 1972 [21]Appl. No.: 243,812

[30] Foreign Application Priority Data Apr. 15, 1971 Great Britain9,535/71 [52] US. Cl. 280/430 [51] Int. Cl B62d 53/12 [58] Field ofSearch.... 280/427, 428, 429, 430, 435

[56] References Cited UNITED STATES PATENTS 1,935,112 11/1933 Connors280/430 1,400,752 12/1921 Land 280/428 Primary ExaminerLeo FriagliaAssistant ExaminerT. L. Siemens Attorney, Agent, or Firm-L. Ros-en eta1.

[ 5 7] ABSTRACT A road-haulage semi-trailer having a sliding king-pinfor lifting the landing legs to the retracted position, the landing legsbeing spring-biassed towards the retracted position and coupled to theking-pin through a rack and pinion to give rapid lifting of the legswith a small king-pin movement. The king-pin is disengageable to moveindependently of the landing legs over a large distance between frontand rear clamps which enable it to be locked in either a front or a rearposition for travelling.

9 Claims, 4 Drawing; Figures PATENTED 4 SHEET 2 BF 4 PATENTED FEB 5 I974SHEET 3 OF 4 KING-PIN ACTUATED LANDING GEARFOR ROAD-HAULAGESEMI-TRAILERS The present invention relates to road-haulage trailers ofthe type which are drawn by a tractor which supports the front end ofthe trailer, and which are commonly referred to as semi-trailers.

It is usual for the coupling between the tractor and the trailer to bemade by means of a king-pin which is fixed to the trailer and projectsdownwardly from the trailer and is engaged by a clamp or fifth-wheelcoupling on the tractor. When the tractor is removed the trailer issupported by landing wheels carried by legs depending from the trailerand provision is usually made for adjusting the vertical height of thelegs or swinging the legs backwards a short way to lift the wheels clearof the ground when the trailer is on the road.

Especially for the very large trailers used for carrying containers theoverall length of the tractor and trailer becomes a problem because ofsafety regulations. For this reason it is desirable for the tractor torun back as far as possible under the trailer but this means displacingthe landing legs towards the rear to avoid the tractor fouling the legswhen turning. This gives rise to the danger of nose-diving" or tippingforward when the tractor is removed because a large part of the weightof the load is forward of the landing wheels.

In US. Patent Specifications Nos. 2,418,240 and 3,456,962 there aredescribed semi-trailers in which the landing legs can be retracted bymeans of a sliding kingpin which is driven rearwards by the tractor ortruck after engagement of the fifth-wheel coupling. Locking mechanismsare provided for holding the landing legs in the retracted position andin the operative position. These constructions do allow the landing legsto be placed further forward on the trailer but they do not allowtrailers with a long rearward extension, for example, three-axletractors, to be used because these will still foul the legs before thelegshave been fully retracted. Moreover, the retraction of the legsrequires the full movement of the sliding king-pin from the front to therear position and this increases the risk of fouling the legs duringretraction and requires that the tractor supports the semi-tractor at apoint some distance to the rear of the front part of the trailer, as aresult of which a substantial part of the load may still be forward ofthe point of support.

It is an object of the present invention to achieve full retraction ofthe legs by a short travel of the sliding king-pin.

In accordance with the invention this is achieved in that the landinglegs are mounted on a transverse shaft mounted in pivotal supports onthe frame of the semitrailer and the transverse shift carries a pinionwhich is in mesh with a rack displaceable by the sliding king-pin.

A further important feature is the provision of a releasable couplingbetween theking-pin and the landing legs which allows completion of themovement of the king-pin to its rear position after the short movementnecessary for retraction of the legs. Preferably also the king-pin canbe disengaged from the landing legs when moving forwards so that thetrailer can be towed by the tractor with the king-pin locked in itsforward position and the landing legs fully retracted.

To facilitate the lifting of the legs to the retracted position by therack and pinion they can be biassed by springs towards the retractedposition, the bias serving 2 the counteract the weight of the landing.legs and wheels.

For securing the sliding king-pin in its front and rear positions, frontand rear clamps are mounted on the trailer to engage with the upper endof the king-pin, the lower end serving for attachment to the tractor. Animportant feature of the invention is the provision of an interlockmechanism between the front and rear clamps which comprises lockingmembers for each clamp and means for disengaging either one of thelocking members while leaving the other locking member ready to engagewhen the open jaws of its clamp are closed by movement of the king-pininto the jaws.

The invention will now be described in more detail with the aid of anexample illustrated in the accompanying drawings, in which:

FIG. 1 is a plan view of the front end of a semi-trailer forming apreferred embodiment of the invention,

FIG. 2 is a detail of FIG. 1 on a larger scale, with parts broken away,

FIG. 3 is a side elevation of the retractable landing wheels and legs ofthe trailer of FIG. 1, and

FIG. 4 is a section on the line llVlV of FIG. 2.

The trailer shown in the drawings has a frame of conventionalconstruction with side members 10 and 11 braced by cross-beams. The rearend of the trailer (beyond the left-hand side of FIG. 1) is supported byroad wheels in conventional manner. Towards the front end of the trailera pair of landing wheels 12 are carried by landing legs 13 which aresecured to a shaft 14 which is mounted in bearings 15 attached to theside members 10 and 11. Each of the legs 13 has a strut 16 (FIG. 3)pivotally attached near the mid-pointof the leg and the other end of thestrut 16 is pivotally attached to a slider 17 which runs in a guidechannel 18 attached to one of the side members of the frame. Acompression spring 19 acting on the slider 17 provides the power forretraction of the wheel 12 and leg 13 from the supporting position shownin full lines to the retracted position shown in broken lines andsupports a majorpart of the weight of the landing wheel and leg in theretracted=position. A spring-loaded latch 20 engaging the slider 17holds each landing leg 13 in its supporting position and in theretracted position of the legs they are held by a locking device 21which hooks on to a cross member 22 extending between the legs 13. Onlya minor partof the weight of the landing wheels and legs falls on thelocking device 21 since the rest is counteracted by the springs 19.

Between the side members 10 and 11 of the frame at the front end of thetrailer a king-pin 23 is fixed in .a block 24 which is slidable betweenguides 25 to trnovle the king-pin between front and rear positions. Theblock is of large dimensions and the guides areofsubstantialconstruction to ensure smooth sliding under load and provision is madeforgreasing the sliding surfaces. The king-pin 23 has alower end 23Awhichisengageable by a clamp mounted on a fifth-wheelplate of a tractor(not shown) and an upper end 23B which can engage with either a frontclamp 26F or a reanclamp 26R on the trailer. The front and rear clampsand associated parts are of the same construction except that the frontclamp faces rearwards and the rear clamp forwards. The parts of the twoclamps are therefore given the same references with the suffixes F(front) ancLR (rear) being used where it is necessary to distinguishbetween them. i

Each of the clamps 26 comprises a pair of jaws 27 and 28 mounted onpivots 29 and 30, respectively, and having semi-circular recesses 31 and32, respectively, for engagement around the upper end 238 of thekingpin. At the side of the pivots remote from the recesses 31 and 32the jaws 27 and 28 have notches 33 and 34, respectively, which areengageable by a head 35 of a locking member 36 to hold the jaws inengagement with the king-pin. Each locking member 36 is biassed by aspring 37 towards engagement between the notches 33 and 34 of the jaws27 and 28. The jaws 27 and 28 are biassed towards the open position bysprings 38 and 39, respectively.

Each locking member 36 can be disengaged from the jaws to allow theclamp to open by means ofa lever 40. The levers 40F and 40R carry pins411-? and 41R running in slots 42F and 42R in links 43F and 43R whichare pivotally attached to opposite arms of a common double bell-cranklever 44. The third arm of the lever 44 is coupled by a link 45 to anoperating lever 46 mounted on the outside of the frame of the trailer.Pulling out of the lever 46 by the operator serves to open whichever ofthe two clamps is closed, in this case the front clamp 26F, bywithdrawing the locking member 36. The slot 42R provides a lost-motionconnection to the pin 41R and hence the locking member 36R remains inthe position shown, with its head 35R resting against the ends of theopen jaws 27R and 28R. When the locking member 36F is withdrawn a stop47F on the lever 40F engages behind a detent 48F on a latch lever 49F toprevent re-engagement of the locking member. The latch lever 49F ispivotally mounted on the frame and'its other end is connected by spring39F to the jaw 28F. An arm 50F to the jaw 28F engages a roller 51F onthe latch lever 49F when the jaws are fully open, thereby tripping thelatch to force the locking member 36F to take up a positioncorresponding to that shown for the locking member 36R.

The king-pin 23 begins in the forward position shown with its upper end233 held by the clamp 26F, the jaws of the clamp 26R being open. Whenthe lower end 23A of the king-pin has been engaged by the clamp of thetractor, the operator pulls out the hand lever 46 to open the clamp 26Fand the tractor then slides the king-pin 23 from the front clamp 26F tothe rear clamp 26R. As the upper end 23 of the king-pin engages therecesses 31R adn 32R in the jaws of the rear clamp it causes the jaws27R and 28R to close around it and the head 35R of the locking member36R springs into the notches 33R and 34R to lock the rear clamp, thussecuring the king-pin in the new position. The front clamp remains openuntil the process is reversed by actuation of the hand lever 46 to openthe rear clamp.

A rod 52 is pivotally coupled to the sliding block 24 in which theking-pin 23 is mounted and extends longitudinally alongthe centre-lineof the trailer. The rod 52 passes through a tubular member 53 to whichis attached a rack 54 which engages a pinion 55 fixed to the shaft 14which carries the landing legs. Rearward movement of the tubular member53 will cause the landing legs 13 to swing to their retracted position.The member 53 has two arms 56 pivotally mounted on its outer surface andhaving projections 561 which pass through slots in the wall of themember 53 and are en 53 the projections 56] are held in engagement withthe of the frame. Thus during the initial rearward movement of the rod52 resulting from sliding of the king-pin out of the front jaws, the rod52 moves the tubular member 53 to effect retraction of the landing legs13. Subsequently, the rod is free to move through the member 53.'Thelocking device 21 is operated by the tubular member 53 through alost-motion connection as the landing legs rise into the fully-retractedposition. To allow retraction of the legs 13 the latch 20 must first bedisengaged and this is done by a cam operated by a linkage 61 coupled tothe lever 40F so that the latch 20 is released when the front jaws 26Fare. opened.

Behind the flange 57 a guide bush 62 surrounds the rod 52 and isslidable within the tubular member 53. The bush 62 is normally heldagainst forward displacement in the member 53 by a stop 63 so that asthe rod 52 is drawn forwards the member 53 is carried with it to lowerthe landing legs as the king-pin 23 enters the front pair of jaws 26F.The stop 63 can be disengaged by a pull-rod 64 to allow the king-pin 23to be locked in the front jaws 26F without the landing legs 13 beinglowered. It is then possible for the trailer to be hauled with theking-pin in the front position.

I claim:

1. In a road-haulage semi-trailer having a sliding king-pin lockable infront and rear positions on the frame of the semi-trailer and coupled tothe landing legs supporting the forward end of the trailer frame toeffect retraction of the legs when the king-pin is slid rearwards byengagement with the tractor, said legs being carried by a transverseshaft mounted in pivotal supports mounted on the frame, the improvementwhich comprises a pinion mounted on said transverse shaft and securedfor rotation therewith, a rack coupled to the sliding king-pin andengageable with the pinion to swing the landing legs to the retractedposition upon displacement of the rack by the king-pin, and means fordisengaging the king-pin from the landing legs to allow movement of theking-pin to the forward position with the legs in the retractedposition.

2. A road-haulage semi-trailer comprising a frame, landing legspivotally mounted on said frame for swinging movement about a pivotaxis, a pinion mounted on said landing legs with its axis of rotationcoincident with the pivot axis, a rack engaging said pinion to swingsaid legs from a supporting to a retracted position, spring meansbiassing said legs to the retracted position, a king-pin slidablymounted on said frame for movement between front and rear positions, areleasable coupling connecting said king-pin to said rack, front andrear clamps mounted on said frame and engageable with the king-pin tolock the king-pin in the front and rear positions respectively, and aninterlock mechanism coupling said front and rear clamps.

3. A semi-trailer as claimed in claim 2 having a slider mounted formovement longitudinally on said frame, and a strut pivotally connectedat one end to the slider and at the other end to the landing legs, saidbiassing spring means acting upon said slider.

4. A semi-trailer as claimed in claim 2 having a locking device forsecuring the landing legs in the retracted position, said locking devicebeing connected for operation by movement of said rack.

5. In a road haulage semi-trailer having a sliding kin gpin lockable infront and rear positions on the frame of the semi-trailer and coupled tothe landing legs supporting the forward end of the trailer frame toeffect retraction of the legs when the king-pin is slid rearwards byengagement with the tractor, said legs being carried by a transverseshaft mounted in pivotal supports mounted on the frame, the improvementwhich comprises a pinion mounted on said transverse shaft and securedfor rotation therewith, a rack coupled to the sliding king-pin andengageable with the pinion to swing the landing legs to the retractedposition upon displacement of the rack by the king-pin, a releasablecoupling between the king-pin and the landing legs, and means forholding said coupling in engagement during retraction of the landinglegs and thereafter releasing said coupling to allow further movement ofthe kingpin to its lockable rear position.

6. In a semi-trailer as claimed in claim 5 said releasable couplingcomprising a tubular member fixed to the rack, a flanged member coupledto the king-pin and displaceable within the tubular member, latch armspivotally mounted on the tubular member and engageable with the flangedmember, and biassing means bias sing said latch arms agianst engagementwith the flanged member, and said holding and releasing means comprisingguides fixed to the frame and cooperating with the latch arms over alimited range of travel of said tubular member to hold said arms inengagement with the flanged member.

7. In a semi-trailer as claimed in claim 5, springs biassing the landinglegs towards the retracted position.

8. In a semi-trailer as claimed in claim 5, front and rear clampsmounted on the frame and engageable with the king-pin to lock it in thefront or rear position, respectively.

9. In a semi-trailer as claimed in claim 8 an interlock mechanismcoupling the front and rear clamps, said interlock mechanism comprisingfront and rear locking members for co-operation with the front and rearclamps, respectively, to hold said clamps in the locked position, andmeans for disengaging one of the locking members while leaving the otherlocking member ready to engage when the open jaws of its clamp areclosed by movement of the king-pin into the jaws.

Patent No UNITED S'IATES IA'IEN'I; OFFICE CERTIFICATE OF CORRECTION I I3 I v Dated ry 5 4 h Carlton John Davis It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

On the cover sheet insert [73] Assignee: Trailer Systems Limited,Rainham, Essex, England Signed and sealed this 1st day of October 1974.

Attest:

C. MARSHALL DANN McCOY M. GIBSON JR. Attesting Officer Commissioner ofPatents USCOMM-DC 60376-P69 u 5. GOVERNMENT PRINTING OFFICE: 869- 930FORM pcmoso (10-69)

1. In a road-haulage semi-trailer having a sliding king-pin lockable infront and rear positions on the frame of the semitrailer and coupled tothe landing legs supporting the forward end of the trailer frame toeffect retraction of the legs when the king-pin is slid rearwards byengagement with the tractor, said legs being carried by a transverseshaft mounted in pivotal supports mounted on the frame, the improvementwhich comprises a pinion mounted on said transverse shaft and securedfor rotation therewith, a rack coupled to the sliding king-pin andengageable with the pinion to swing the landing legs to the retractedposition upon displacement of the rack by the king-pin, and means fordisengaging the king-pin from the landing legs to allow movement of theking-pin to the forward position with the legs in the retractedposition.
 2. A road-haulage semi-trailer comprising a frame, landinglegs pivotally mounted on said frame for swinging movement about a pivotaxis, a pinion mounted on said landing legs with its axis of rotationcoincident with the pivot axis, a rack engaging said pinion to swingsaid legs from a supporting to a retracted position, spring meansbiassing said legs to the retracted position, a king-pin slidablymounted on said frame for movement between front and rear positions, areleasable coupling connecting said king-pin to said rack, front andrear clamps mounted on said frame and engageable with the king-pin tolock the king-pin in the front and rear positions respectively, and aninterlock mechanism coupling said front and rear clamps.
 3. Asemi-trailer as claimed in claim 2 having a slider mounted for movementlongitudinally on said frame, and a strut pivotally connected at one endto the slider and at the other end to the landing legs, said biassingspring means acting upon said slider.
 4. A semi-trailer as claimed inclaim 2 having a locking device for securing the landing legs in theretracted position, said locking device being connected for operation bymovement of said rack.
 5. In a road haulage semi-trailer having asliding king-pin lockable in front and rear positions on the frame ofthe semi-trailer and coupled to the landing legs supporting the forwardend of the trailer frame to effect retraction of the legs when theking-pin is slid rearwards by engagement with the tractor, said legsbeing carried by a transverse shaft mounted in pivotal supports mountedon the frame, the improvement which comprises a pinion mounted on saidtransverse shaft and secured for rotation therewith, a rack coupled tothe sliding king-pin and engageable with the pinion to swing the landinglegs to the retracted position upon displacement of the rack by theking-pin, a releasable coupling between the king-pin and the landinglegs, and means for holding said coupling in engagement duringretraction of the landing legs and thereafter releasing said coupling toallow further movement of the king-pin to its lockable rear position. 6.In a semi-trailer as claimed in claim 5 said releasable couplingcomprising a tubular member fixed to the rack, a flanged member coupledto the king-pin and displaceable within the tubular member, latch armspivotally mounted on the tubular member and engageable with the flangedmember, and biassing means biassing said latch arms agianst engagementwith the flanged member, and said holding and releasing means comprisingguides fixed to the frame and co-operating with the latch arms over alimited range of travel of said tubular member to hold said arms inengagement with the flanged member.
 7. In a semi-trailer as claimed inclaim 5, springs biassing the landing legs towards the retractedposition.
 8. In a semi-trailer as claimed in claim 5, front and rearclamps mounted on the frame and engageable with the king-pin to lock itin the front or rear position, respectively.
 9. In a semi-trailer asclaimed in claim 8 an interlock mechanism coupling the front and rearclamps, said interlock mechanism comprising front and rear lockingmembers for co-operation with the front and rear clamps, respectively,to hold said clamps in the locked position, and means for disengagingone of the locking members while leaving the other locking member readyto engage when the open jaws of its clamp are closed by movement of theking-pin into the jaws.